Method for determining an optical parameter of a lens

ABSTRACT

A method implemented by computer means for determining at least one optical parameter of a lens of eyewear adapted for a person, the method comprising: —an image reception step, during which at least a first image and a second image are received, the first image comprising a front view of the face of the person with at least one part of an eye of the person being directly visible, and the second image comprising a front view of the face of the person with said part of the eye of the person being visible through at least part of the lens, and —an optical parameter determination step, during which at least one optical parameter of the lens is determined based on a comparison between said part on the first and the second image.

FIELD OF THE INVENTION

The invention relates to a method implemented by computer means fordetermining at least one optical parameter of a lens of eyewear adaptedfor a person, to a method for ordering a lens of eyewear adapted for aperson, to a computer program product able to perform the method of theinvention and to a system comprising at least a reception unit, anelectronic storage medium and a processing unit, the electronic storagemedium carrying the instructions of the computer program product.

BACKGROUND OF THE INVENTION

Usually, a person wishing to have an optical equipment goes over to aneye care practitioner.

The eye care practitioner orders the eyewear equipment at an optical labby sending an order request to the optical lab. The order request maycomprise wearer data, for example the wearer's prescription, fittingdata, spectacle frame data, for example the type of spectacle frame thewearer has selected, and lens data, for example the type of optical lensthe wearer has selected.

The determination of the wearer's prescription and fitting data mayrequire carrying out complex and time-consuming measurements. Suchmeasurements usually require complex and costing material and qualifiedpersonnel to be carried out.

Such measurements are usually carried out even when the person's opticalneeds have not changed. For example, a person that wants to order a newframe with the same optical lenses than with his/her previous spectaclesmay have to go through the tedious process indicated previously.

Indeed, some fitting data are directly linked to the frame. In addition,regarding the wearer's prescription and other wearer data such as thepupillary distance, the results of former measurements by the eye carepractitioner may be lost.

The eye care practitioner may use lens mapper and/or lens meter todetermine the optical features of the current optical lenses of theoptical equipment of the person. However, such devices still requiregoing to the eye care practitioner since there are very expensive andrequire qualified person to be used. In other words, the person himselfmay not use such devices to determine the parameters to be included inthe order request. Typically, such devices are not available when aperson wishes to order a new optical equipment over the internet.

Therefore, there is a need to a method and a device that would allow aperson to quickly, easily and at low cost determine optical parametersof his/her current optical equipment.

One object of the present invention is to provide such method.

SUMMARY OF THE INVENTION

To this end, the invention proposes a method implemented by computermeans for determining at least one optical parameter of a lens ofeyewear adapted for a person, the method comprising:

-   -   an image reception step, during which at least a first image and        a second image are received, the first image and the second        image each comprise a front view of the face of the person with        at least one part of an eye of the person being visible, and        said part of the eye of the person is visible through at least        part of the lens at least on the second image, and    -   an optical parameter determination step, during which at least        one optical parameter of the lens is determined based on a        comparison between said part on the first and the second image.

Advantageously, the invention allows a person to determine opticalparameters of his/her current equipment quickly, easily, at low cost andwithout a professional's assistance.

According to further embodiments of the optical device according to theinvention which can be considered alone or in combination:

-   -   during the image reception step, the first image comprises a        front view of the face of the person with at least one part of        an eye of the person being directly visible, and the second        image comprises a front view of the face of the person with said        part of the eye of the person being visible through at least        part of the lens; and/or    -   during the image reception step, the first image and the second        image both comprise a front view of the face of the person with        at least one part of an eye of the person being visible through        at least part of the lens, the first image corresponds to a        first eye-lens distance between the lens and said part of the        eye, the second image corresponds to a second eye-lens distance        between the lens and said part of the eye, and the second        eye-lens distance is different from the first eye-lens distance;        and/or    -   during the optical parameter determination step, the optical        parameter of the lens is determined based on a comparison on the        deformation of said part of the eye between the first and the        second image; and/or    -   on the second image, the person is wearing the eyewear with the        lens, or holding the eyewear with the lens in front of his face;        and/or    -   said part of the eye includes iris or pupil; and/or    -   on the first image, an object with at least one known dimension,        such as a credit card, is positioned in the same plane as said        part of the eye of the person; and/or    -   on the second image, an object of at least one known dimension,        such as a credit card, is positioned in a plane tangent to the        lens at a reference point chosen on the front surface of said        lens; and/or    -   during the image reception step, a third image is received, the        third image comprising a view of the eyewear positioned on a        flat surface along with an object with at least one known        dimension, such as a credit card; and/or    -   during the image reception step, a fourth image is received, the        fourth image comprising a side view of the face of the person,        wearing the eyewear, said part of the eye of the person is        directly visible; and/or    -   during the image reception step, a fifth image is received, the        fifth image comprising a side view of the face of the person        wearing the eyewear; and/or    -   the invention further comprises a first image acquisition step,        during which the first image is acquired by a portable        electronic device comprising an image acquisition module; and/or    -   the invention further comprises a lens positioning step, during        which the lens is positioned relatively to said part of the eye        of the person at a position corresponding to the second image;        and/or    -   the invention further comprises a second image acquisition step        during which the second image is acquired by the portable        electronic device comprising the image acquisition module;        and/or    -   the invention further comprises, prior to the first image        acquisition step, a first lens positioning step, during which        the lens is positioned relatively to said part of the eye of the        person at a position corresponding to the first image; and/or        the invention further comprises a third image acquisition step        for acquiring the third image by a portable electronic device        comprising an image acquisition module; and/or    -   the invention further comprises a fourth image acquisition step        for acquiring the fourth image by the portable electronic        device; and/or    -   the invention further comprises a fifth image acquisition step        for acquiring the fifth image by the portable electronic device;        and/or    -   the invention further includes a scaling step, during which,        when the person wears the optical equipment, the distance        between said part of the eye of the person and the lens, and the        distance from which the lens is seen on at least one image        received during the image reception step are determined        relatively to at least one known dimension, and during the        optical parameter determination step, the at least one optical        parameter of the lens is determined based on the distance        between said part of the eye of the person and the lens, and the        distance from which the lens is seen on at least one image        received during the image reception step; and/or    -   the first image and the second image are acquired in similar        viewing conditions; and/or    -   the first image, the second image and the fourth image are        acquired in similar viewing conditions; and/or    -   the invention further includes a viewing condition reception        step, during which at least a first viewing condition and a        second viewing condition are received, the first viewing        condition being associated to the first image and the second        viewing condition being associated to the second image; and/or    -   during the viewing condition reception step, a third viewing        condition is received, the third viewing condition being        associated to the third image; and/or    -   during the viewing condition reception step, a fourth viewing        condition is received, the fourth viewing condition being        associated to the fourth image; and/or    -   during the viewing condition reception step, a fifth viewing        condition is received, the fifth viewing condition being        associated to the fifth image; and/or    -   the invention further includes a viewing condition determination        step, during which at least a first viewing condition and a        second viewing condition are determined, the first viewing        condition being associated to the first image and the second        viewing condition being associated to the second image; and/or    -   during the viewing condition determination step, a third viewing        condition is determined, the third viewing condition being        associated to the third image; and/or    -   during the viewing condition determination step, a fourth        viewing condition is determined, the fourth viewing condition        being associated to the fourth image; and/or    -   during the viewing condition determination step, a fifth viewing        condition is determined, the fifth viewing condition being        associated to the fifth image; and/or    -   the viewing condition includes a lighting parameter; and/or    -   the viewing condition includes a refraction parameter; and/or    -   the viewing condition includes a reflection parameter; and/or    -   during the optical parameter determination step, the at least        one optical parameter of the lens is determined based on the        lighting parameter of at least two of the first image and the        second image and the fourth image; and/or    -   the portable electronic device is a smartphone, a personal        digital assistant, a laptop, a webcam or a tablet computer;        and/or    -   the optical parameter of the lens comprises the dioptric        function of the optical lens; and/or    -   the optical parameter of the lens comprises the optical power in        a visual reference zone of the optical lens; and/or    -   the optical parameter of the lens comprises the optical cylinder        in a visual reference zone of the optical lens; and/or    -   the optical parameter of the lens comprises the optical cylinder        axis in a visual reference zone of the optical lens; and/or    -   the optical parameter of the lens comprises the prism base in a        visual reference zone of the optical lens; and/or    -   the optical parameter of the lens comprises the prism axis in a        visual reference zone of the optical lens; and/or    -   the optical parameter of the lens comprises the type of optical        design of the optical lens; and/or    -   the optical parameter of the lens comprises the transmittance of        the optical lens; and/or    -   the optical parameter of the lens comprises the color of the        optical lens.

Another object of the invention is a method for ordering a lens ofeyewear adapted for a person, comprising:

-   -   an optical parameter determining step, during which at least one        optical parameter of the lens is determined by a method        implemented by computer means for determining at least one        optical parameter of a lens of eyewear adapted for a person        according to the invention, and    -   an ordering step, during which a lens having the at least one        determined optical parameter is ordered.

Another object of the invention is a computer program product comprisingone or more stored sequences of instructions which, when executed by aprocessing unit, are able to perform the parameter determining step ofthe method according to the invention.

Another object of the invention is a system comprising at least areception unit, an electronic storage medium and a processing unit,

-   -   the reception unit, the electronic storage medium and the        processing unit being configured so as to communicate one with        another,    -   the reception unit being able to receive a first and a second        image,        -   the first image comprising a front view of the face of the            person with said part of the eye of the person being            directly visible, and        -   the second image comprising a front view of the face of the            person with said part of the eye of the person being visible            through at least part of the lens, and    -   the electronic storage medium comprising one or more stored        sequences of instructions which, when executed by the processing        unit, are able to perform an optical parameter determination        step, during which at least one optical parameter of a lens is        determined based on a comparison between at least one part of an        eye of a person on the first and the second image.

The invention further relates to a computer program product comprisingone or more stored sequences of instructions that are accessible to aprocessor and which, when executed by the processor, causes theprocessor to carry out at least the steps of the method according to theinvention.

The invention also relates to a computer-readable storage medium havinga program recorded thereon; where the program makes the computer executeat least the steps of the method of the invention.

The invention further relates to a device comprising a processor adaptedto store one or more sequences of instructions and to carry out at leaststeps of the method according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention will now be described, by wayof example only, and with reference to the following drawings in which:

FIGS. 1A, 1B and 1C are schematic diagrams of the steps of a method fordetermining an optical parameter of a lens according to embodiments ofthe invention;

FIGS. 2A-2E show examples of images received during the reception stepof a method according to an embodiment of the invention;

FIGS. 3A-3D show examples of image acquisition steps of a methodaccording to an embodiment of the invention;

FIGS. 4 and 5A-5B show examples of images received during the receptionstep comprising an object with at least one known dimension, accordingto an embodiment of the invention;

FIGS. 5C-5D show examples of image acquisition steps, wherein the imagesshow an object with at least one known dimension, according to anembodiment of the invention;

FIG. 6 is a schematic diagram of the steps of a method for ordering alens of eyewear adapted for a person according to the invention; and

FIG. 7 is a schematic diagram of a system comprising at least areception unit, an electronic storage medium and a processing unit, theelectronic storage medium carrying the instructions of a computerprogram product able to perform a method according to the invention.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensions ofsome of the elements in the figure may be exaggerated relative to otherelements to help improve the understanding of the embodiments of thepresent invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The invention relates to a method implemented by computer means fordetermining at least one optical parameter of a lens of eyewear adaptedfor a person.

The at least one optical parameter of the lens may include the type oflens, such as single vision, bifocal or progressive.

The at least one optical parameter of the lens may include at least oneparameter of the dioptric function of the lens.

The at least one optical parameter of the lens may include at least oneparameter of the optical design of the lens, such as the distribution ofoptical power on the surface of the lens.

The lens may include a progressive lens and the at least one opticalparameter of a lens may include at least one of the following: corridor,far vision and near vision points, sphere, cylinder, cylinder axis,prism base, prism axis, transmittance and color.

The at least one optical parameter of the lens may be determined for avisual reference zone of the lens. The visual reference zone maygenerally correspond to an upper or a lower zone of the lens.

As illustrated on FIG. 1, the method comprises at least an imagereception step S12 and an optical parameter determination step S16.

During the image reception step S12, at least a first image and a secondimage are received.

By image is understood any image type or image format. Images includetwo-dimensional images or three-dimensional images such as depth mapsgenerated from stereo images, from light-field images or from video.

The first image and the second image each comprise a front view of theface of the person with at least one part of an eye of the person beingvisible. Said part of the eye of the person is visible through at leastpart of the lens at least on the second image.

In some embodiments, on the first image said part 2 of the eye of theperson is directly visible, as illustrated on FIG. 2A.

In other embodiments, on the first image and the second image bothcomprise a front view of the face of the person with at least one part 2of an eye of the person being visible through at least part of the lens4, the first image corresponds to a first eye-lens distance between thelens 4 and said part 2 of the eye, the second image corresponds to asecond eye-lens distance between the lens 4 and said part 2 of the eye,and the second eye-lens distance is different from the first eye-lensdistance.

By view is understood a graphical projection of a three-dimensionalobject onto a planar surface which is referred to in this document as aplan image.

On an image comprising a front view of the face of the person, thepositioning of the iris within the eye corresponds to a gaze directionperpendicular to the plan image.

An object such as said part 2 of the eye of the person being directlyvisible on an image is understood as said object being separated fromthe plan image by a straight line which is not interrupted by anyphysical obstacle.

Said part 2 of the eye of the person being seen through at least part ofthe lens 4 is understood as being present on the second image behindsaid at least part of the lens 4.

Said part 2 of the eye of the person may include the iris or the pupil.A particularly advantageous effect is that the determination of theshape and dimensions of the iris and of the pupil is easy and accuratedue to a high contrast difference between the iris and the white of theeye and/or, depending on the color of the iris, between the pupil andthe iris.

On the second image, the person may be wearing an eyewear with the lens4.

Alternatively, the person may be holding an eyewear with the lens 4 at adistance in front of his face. Said distance may for example be measuredby any method known to the person skilled in the art. Said distancecould be for example equal to the length of the temple of the frame.

An increased distance between said part 2 of the eye of the person andthe lens 4 results in an increased deformation of said part 2 of the eyeof the person on the second image, compared to the first image. Providedthat the increased deformation does not lead to said part 2 of the eyeof the person appearing too small on the second image with respect tothe resolution of the second image, a better accuracy of the method isreached.

During the optical parameter determination step S16, at least oneoptical parameter of the lens is determined based on a comparisonbetween said part 2 on the first and the second image.

For example, by comparing the color of said part 2 of the eye on thefirst and the second image, it is possible to determine opticalparameters of the lens related to color.

According to an embodiment, said optical parameter of the lens isdetermined based on a comparison on the deformation of said part 2 ofthe eye of a person between the first image and the second image. In thesense of the invention, deformation is a change in dimensions and/or inshape.

In the case where the first image comprises a direct view of the part 2of the eye of the user, the algorithm used to perform the opticalparameter determination step S16 requires values of the followingdistances:

-   -   the distance between said part 2 of the eye and the image        acquisition module used to acquire the first image while the        first image was acquired, and    -   the distance between said part 2 of the eye and the lens 4 while        the second image was acquired.

In the case where both the first and the second image comprise a view ofthe part 2 of the eye of the user through the lens 4, the algorithm usedto perform the optical parameter determination step S16 requires valuesof the distance between the lens 4 and the image acquisition module usedto acquire the first image while the first image was acquired and of thedistance between the lens 4 and the image acquisition module used toacquire the second image while the second image was acquired.

In the case where the first image and the second image are both depthmaps or other images obtained by mapping or facial recognitiontechnologies, such as the technologies implemented in Kinect or Face ID,the images may comprise depth information, thus the required values maybe enclosed in the images, extracted from the image data and determinedrelatively to each other.

In the case where the first image and the second image are bothtwo-dimensional images such as photographs, the required values may bedetermined either relatively to each other or as absolute numericalvalues.

The required values may be predetermined, for example at least onedefault value may be entered.

Alternatively, the required values may be input manually by the person.

Alternatively, the required values may be selected in a database, basedon manual inputs by the person and/or based on at least one image.

Alternatively, according to another embodiment, the method according tothe invention may further include a scaling step S14.

During the scaling step S14, the required values for the calculationsare determined relatively to at least one known dimension. The requiredvalues are determined based at least on the first and the second images.Said known dimension is to be understood as either the known length ofan object, or the known distance between two objects.

The required values for the calculations may be determined based oncalibration. Calibration consists in using an object whose size is knownto know the dimension of other objects in a photo.

An object having one known dimension may be a credit card, or any objectwhich may be referenced in a database comprising a list of objects andat least their corresponding lengths. An example of such objects is aspectacle frame. In this case, the person may for example select thespectacle frame he/she is wearing in a database comprising a list ofspectacle frames and their corresponding lengths. Some dimensions of theframe may also be read directly on the frame. In this example, thecalibration can be done directly during the acquisition of at least thefirst and second images.

Alternatively, an object having one known dimension may be an objectwhich itself is calibrated with another object having one knowndimension.

According to an embodiment, during the image reception step S12, a thirdimage may be received, the third image comprising, as illustrated onFIG. 2C, a view of the eyewear comprising the lens 4. The eyewear ispositioned on a flat surface along with an object 6 with at least oneknown dimension, such as a credit card. Thus the absolute dimensions andshape of the eyewear may be determined and the eyewear may be furtherused, on other images, as a scale. Advantageously, this image may beused to perform a calibration of the spectacle frame prior to thescaling step S14.

The following example illustrates an embodiment of the invention inwhich the method comprises a scaling step S14.

In this example, during the reception step S12, three imagescorresponding to the following description are received:

-   -   the first image, as illustrated on FIG. 5A, is a front view of        the person having a spectacle frame at the level of his forehead        and a credit card positioned in the same plane as a part 2 of        the eye of the person, the first image is acquired by an image        acquisition module positioned at a distance d1 from the part 2        of the eye of the person,    -   the second image, as illustrated on FIG. 5B, is a front view of        the person having the spectacle frame on his nose so that the        lens 4 is before the part 2 of the eye of the person and a        credit card positioned in a plane tangent to the lens 4 at a        reference point chosen on the front surface of said lens 4, the        second image is acquired by an image acquisition module        positioned a distance d2 from the part 2 of the eye of the        person, and    -   the third image is a front view of the person having the        spectacle frame at the level of his forehead, the third image is        acquired by an image acquisition module positioned a third        distance d3 from the part 2 of the eye of the person.

Any of the distances d1, d2 and d3 may be equal to or different fromeach other.

In this example, the credit card is an object 6 of one known dimension,this known dimension is in the same plane as the part 2 of the eye ofthe person on the first image. Therefore the credit card may be used todetermine the dimensions of said part 2 of the eye of the person on thefirst image.

Moreover, in this example, the known dimension of the credit card is ina plane tangent to the lens 4 at a reference point chosen on the frontsurface of said lens 4 on the second image. Therefore, the dimensions ofthe spectacle frame are calibrated with the credit card based on thesecond image, thus the spectacle frame is also an object of at least oneknown dimension, which may be used to determine the dimensions of saidpart 2 of the eye of the person as seen on the second image.

Furthermore, either the credit card or the spectacle frame may be usedto determine characteristic dimensions of the face of the person.

In this example, during the scaling step S14, the distance d1 betweensaid part 2 of the eye and the image acquisition module used to acquirethe first image while the first image was acquired, and the distancebetween said part 2 of the eye and the lens 4 while the second image wasacquired are determined based on the acquired images.

In this example, during the optical parameter determination step S16, atleast one optical parameter of the lens is determined based on acomparison between said part 2 on the first and the second image andbased on the distances determined during the scaling step S14.

The method may further include an image data providing step S13.

During the image data providing step S13, image data are provided forthe first and the second images. The image data comprise a dimensionrelating at least to characteristics, such as settings or technicalspecifications, of the image acquisition device used to acquire eachimage.

In the following example illustrated on FIG. 4, we consider thefollowing dimensions or distances:

-   -   L_(PD) is the interpupillary distance of the person,    -   L_(M) is the length of an object, here a spectacle frame of        eyewear with the lens 4,    -   L′_(PD) is, in the plan image of the second image, the distance        corresponding to the interpupillary distance of the person,    -   L′_(M) is, in the plan image of the second image, the distance        corresponding to the length of the object on the second image,    -   d_(VO) is the distance between the optical lens and the part 2        of the eye of the person,    -   d is the distance between the lens 4 and the lens of the image        acquisition device which acquired the second image, and    -   f′_(C) is the focal length of the lens of the image acquisition        device, represented as a pinhole camera, which acquired the        second image.

Among these values, the required distances for the calculations duringthe optical parameter determining step S16 are d_(VO) and d.

L′_(M) and L′_(PD) are dimensions which may be determined directly fromthe second image. f′_(C) is a dimension related to the image acquisitiondevice.

L_(PD) may be a known dimension, for example separately provided,measured, or determined in a similar manner from the first image if thefirst image comprises a view of both eyes directly seen.

d_(VO) may be determined using the equationd_(VO)=d(L_(PD)/L′_(PD)×L′_(M)/L′_(M)−1).

According to an embodiment, during the image reception step S12, afourth image may be received. The fourth image comprises, as illustratedon FIG. 2D, a side view of the face of the person, with the lens 4 beingin the same position with regard to said part 2 of the eye as on thefirst image.

By side view is understood a view in which the head of the person isoriented to the side. In other words, on the fourth image, the center ofsaid part 2 of the eye and the center of the lens 4 are on a straightline substantially parallel to the plan image.

Advantageously, characteristic side-view dimensions on the head of theperson may be determined. In particular, through the association of thethird and the fourth image, characteristic side-view dimensions on thehead of the person may be scaled relatively to the dimensions of theeyewear.

On the fourth image, said part 2 of the eye of the person may bedirectly visible. Advantageously, in this case the distance between saidpart 2 of the eye of the person and the lens 4 may be determined. Inparticular, through the association of the third and the fourth image,the distance between said part 2 of the eye of the person and the lens 4may be scaled relatively to the dimensions of the eyewear.

According to an embodiment, during the image reception step S12, a fifthimage may be received, the fifth image comprising, as illustrated onFIG. 2E, a side view of the face of the person, wherein said part 2 ofthe eye is directly visible.

Advantageously, if said part 2 of the eye is not directly visible on thefourth image, it is possible from the fifth image to determine theposition of said part 2 of the eye of the person on the fourth image asif it was directly visible.

Thus, the distance between the lens 4 and said part 2 of the eye may bedetermined. It may be assumed that this distance is the same on everyimage where the person is wearing the eyewear, for example on the secondimage.

In addition, the method according to the invention may further include aviewing condition reception step S10.

During the viewing condition reception step, at least two viewingconditions associated to different images may be received. The viewingconditions may be metadata included in an image. Advantageously, viewingconditions associated to every image may be received.

Viewing conditions may include a lighting parameter, which may includeat least a value in a radiometry unit or in a photometry unit.

Viewing conditions may include a reflection parameter. For example, animage may be reflected from a mirror.

In an embodiment, the viewing conditions are similar for the first imageand the second image.

Alternatively, the method according to the invention may further includea viewing condition determination step S11.

During the viewing condition determination step, at least two viewingconditions associated to different images may be determined. As anexample of a viewing condition, a lighting parameter, such asbrightness, may be determined by image treatment of at least part of animage. Advantageously, viewing conditions associated to every image maybe determined.

For this reason, it is possible to use some characteristic distancesmeasured on the face to determine a ratio factor between differentimages.

The viewing conditions may also include the distance between the imageacquisition module and an element such as the lens 4 or the part 2 ofthe eye of the person while each image is acquired. Indeed, suchdistances may be different from an image to another.

The scaling step S14 and/or the optical parameter determination step S16may also be adapted based on the viewing conditions.

For example, if the face has not the same size in photo 1 withoutglasses and photo 2 with eyeglasses, this implies that the distancebetween the image acquisition module and the face has changed. A ratiofactor may thus be calculated to take into account for the powercalculation.

Alternatively, differences in viewing conditions, such as brightness,between two images may result in a deformation of the part 2 of the eye,the deformation being independent from the lens 4. Thus the differencein apparent shape or dimensions of the image of said part of the eye ondifferent images may be corrected from the variations in the viewingconditions.

In an embodiment, the method according to the invention may alsocomprise a first image acquisition step S2, as illustrated on FIG. 3A,during which a first image is acquired by a portable electronic device 8comprising an image acquisition module 10.

FIG. 5C illustrates a specific embodiment in which during the firstimage acquisition step S2, an object 6 of at least one known dimensionis positioned so that on the first image, said part 2 of the eye of theperson and at least one known dimension of the object 6 are in the sameplane.

In an embodiment, the portable electronic device 8 is a smartphone, apersonal digital assistant, a laptop, a webcam or a tablet computer. Theportable electronic device may comprise a battery, and may communicatewith a reception unit, for example by wireless communication.Advantageously, the image acquisition step S2 may be carried out easilyin any location.

The method may comprise a lens positioning step S3, during which thelens 4 is positioned relatively to said part 2 of the eye of the personat a position corresponding to the second image.

The method may comprise a second image acquisition step S4, asillustrated on FIG. 3B, during which a second image is acquired by theportable electronic device 8 comprising the image acquisition module 10,wherein the image acquisition module 10 is positioned at a seconddistance from the lens 4.

During the second image acquisition step S4, the face of the person, thelens 4 and the image acquisition module 10 are positioned in such a waythat said part 2 of the eye of the person is visible from the imageacquisition module 10 through at least part of the lens 4.

In an embodiment, the method further comprises, prior to the first imageacquisition step S2, a first lens positioning step S1, during which thelens 4 is positioned relatively to the part 2 of the eye of the personat a position corresponding to the first image. Thus the inventionallows a person to determine optical parameters of his/her eyewear forexample by simply using his/her smartphone, or another portableelectronic device, to take a series of images of his/her face with andwithout eyewear, then having the images processed.

As illustrated on FIG. 5D, during the second image acquisition step S4,a reference element with at least one known dimension in a plane may bepositioned so that on the second image the known dimension is in a planetangent to the lens 4 at a reference point chosen on the front surfaceof said lens 4.

Advantageously, the method according to the invention may include athird image acquisition step S6 for acquiring a third image by aportable electronic device 8 comprising an image acquisition module 10.

Advantageously, the method according to the invention may include afourth image acquisition step S8, as illustrated on FIG. 3C, foracquiring a fourth image by a portable electronic device 8 comprising animage acquisition module 10.

Advantageously, the method according to the invention may include afifth image acquisition step S9, as illustrated on FIG. 3D for acquiringa fifth image by a portable electronic device 8 comprising an imageacquisition module 10.

The invention may further relate to a method for ordering a second lensof eyewear adapted for a person, as illustrated on FIG. 6.

The method comprises at least an optical parameter determining step S17and an ordering step S18.

During the optical parameter determining step S17, at least one opticalparameter of a first lens is determined by a method according to theinvention, as illustrated on FIG. 1.

During the ordering step S18, a second lens having the at least onedetermined optical parameter of the first lens is ordered.

The invention may further relate to a computer program productcomprising one or more stored sequences of instructions which, whenexecuted by a processing unit 20, are able to perform at least theoptical parameter determining step S16 of the invention.

The invention may further relate, as illustrated on FIG. 7, to a systemcomprising at least a reception unit 22, an electronic storage medium 24and a processing unit 20,

-   -   the reception unit 22, the electronic storage medium 24 and the        processing unit 20 being configured so as to communicate one        with another,    -   the reception unit 22 being able to receive a first image and a        second image,        -   the first image comprising a front view of the face of the            person with said part 2 of the eye of the person being            directly visible, and        -   the second image comprising a front view of the face of the            person with said part 2 of the eye of the person being            visible through at least part of the lens 4, and    -   the electronic storage medium 24 comprising one or more stored        sequences of instructions which, when executed by the processing        unit 20, are able to perform an optical parameter determination        step S16, during which at least one optical parameter of a lens        4 is determined based on a comparison between at least one part        2 of an eye of a person on the first image and the second image.

The system may further comprise image acquisition means configured so asto communicate at least with the reception unit, the image acquisitionmeans being able to acquire the first image and the second image.

Examples of such systems may include a smartphone, a laptop computer, adesktop computer, a tablet computer or a personal digital assistant.

The invention has been described above with the aid of embodimentswithout limitation of the general inventive concept.

Many further modifications and variations will suggest themselves tothose skilled in the art upon making reference to the foregoingillustrative embodiments, which are given by way of example only andwhich are not intended to limit the scope of the invention, that beingdetermined solely by the appended claims.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. The mere fact that different features are recited in mutuallydifferent dependent claims does not indicate that a combination of thesefeatures cannot be advantageously used. Any reference signs in theclaims should not be construed as limiting the scope of the invention.

The invention claimed is:
 1. A method implemented by computer means fordetermining at least one optical parameter of a lens of eyewear adaptedfor a person, the method comprising: an image reception step, duringwhich at least a first image and a second image are received, the firstand second images are depth maps comprising depth information, the firstimage and the second image each comprise a front view of a face of theperson with at least one part of an eye of the person being visible, andsaid part of the eye of the person is visible through at least part ofthe lens on the second image, an optical parameter determination step,during which first and second image data are extracted from respectivedepth information and compared together to determine at least oneoptical parameter of the lens.
 2. The method according to claim 1,wherein during the image reception step, the first image comprises afront view of the face of the person with at least one part of an eye ofthe person being directly visible, and the second image comprises afront view of the face of the person with said part of the eye of theperson being visible through at least part of the lens.
 3. The methodaccording to claim 1, wherein during the image reception step, the firstimage and the second image both comprise a front view of the face of theperson with at least one part of an eye of the person being visiblethrough at least part of the lens, the first image corresponds to afirst eye-lens distance between the lens and said part of the eye, thesecond image corresponds to a second eye-lens distance between the lensand said part of the eye, and the second eye-lens distance is differentfrom the first eye-lens distance.
 4. The method according to claim 1,further comprising: a first image acquisition step, during which thefirst image is acquired by a portable electronic device comprising animage acquisition module, a lens positioning step, during which the lensis positioned relatively to said part of the eye of the person at aposition corresponding to the second image, and a second imageacquisition step during which the second image is acquired by theportable electronic device comprising the image acquisition module. 5.The method according to claim 4, further comprising prior to the firstimage acquisition step: a first lens positioning step, during which thelens is positioned relatively to said part of the eye of the person at aposition corresponding to the first image.
 6. The method according toclaim 4, wherein during the image reception step, a third image isreceived, the third image comprising a side view of the face of theperson, wearing the eyewear, wherein said part of the eye of the personis directly visible.
 7. The method according to claim 6, wherein duringthe image reception step, a fourth image is received, the fourth imagecomprising a side view of the face of the person, wherein the person iswearing the eyewear.
 8. The method according to claim 7, furthercomprising: acquiring a fifth image including a view of the eyewearpositioned on a flat surface along with an object with at least oneknown dimension by a portable electronic device comprising an imageacquisition module, acquiring the third image comprising the side viewof the face of the person, wearing the eyewear, wherein said part of theeye of the person is directly visible, by the portable electronicdevice, a fourth image acquisition step for acquiring the fourth imagecomprising the side view of the face of the person, wherein the personis wearing the eyewear, by the portable electronic device.
 9. The methodaccording to claim 1, wherein said part of the eye includes iris orpupil.
 10. The method according to claim 1, wherein on the first image,an object with at least one known dimension, such as a credit card, ispositioned in the same plane as said part of the eye of the person. 11.The method according to claim 10, further including: a scaling step,during which, when the person wears the eyewear, a distance between saidpart of the eye of the person and the lens, and the distance from whichthe lens is seen on at least one image received during the imagereception step are determined relatively to at least one knowndimension, and wherein during the parameter determination step, the atleast one optical parameter of the lens is determined based on thedistance between said part of the eye of the person and the lens, andthe distance from which the lens is seen on at least one image receivedduring the image reception step.
 12. The method according to claim 1,wherein on the second image, an object of at least one known dimension,such as a credit card, is positioned in a plane tangent to the lens at areference point chosen on the front surface of said lens.
 13. The methodaccording to claim 1, wherein during the image reception step, a thirdimage is received, the third image comprising a view of the eyewearpositioned on a flat surface along with an object with at least oneknown dimension.
 14. A method for ordering a lens of eyewear adapted fora person, comprising: an optical parameter determining step, duringwhich at least one optical parameter of the lens is determined by themethod according to claim 1, and an ordering step, during which an lenshaving the at least one determined optical parameter is ordered.
 15. Asystem comprising at least a receiver, an electronic storage medium, anda processor, the receiver, the electronic storage medium and theprocessor being configured to communicate one with another, the receiverbeing able to receive a first and a second image, the first image is adepth map comprising depth information and comprising a front view ofthe face of a person with part of an eye of the person being directlyvisible, and the second image is a depth map comprising depthinformation and comprising a front view of the face of the person withsaid part of the eye of the person being visible through at least partof a lens, and the electronic storage medium comprising one or morestored sequences of instructions which, when executed by the processor,are able to perform an optical parameter determination step, duringwhich first and second image data are extracted from respective depthinformation and compared together to determine at least one opticalparameter of a lens.